Increases in storage capacity make it unnecessary to delete emails. Organizing the resulting large volume of email messages, however, presents significant challenges. For example, users or custodians may not be willing to make the effort to store their emails in different folders. Leaving emails in a single folder, however, may result in a frustrating user experience. In another example, an authorized person may desire to group or otherwise organize emails from multiple users or custodians. Accordingly, there is a need for ways to organize emails efficiently.